Epilepsy patients who are candidates for surgical resection of a brain lesion must have some form of functional mapping to determine if the lesion can be removed without creating a functional deficit. The current procedures for mapping language functional areas in these patients are either spatially limited (hemispheric mapping with the Wada test for example) or highly invasive (cortical stimulation using subdural electrodes). Functional MR imaging (fMRI) has the potential to replace the current methods used in Neurosurgical planning. It is completely noninvasive and has been shown to be able to detect functional brain regions. However, the standard echo planar imaging fMRI methods, based on the BOLD activation response, suffer from low spatial resolution, and a sensitivity to static Bomicron magnetic field inhomogeneities which lead to geometric image distortions and low signal intensity. These problems severely limit the ability of fMRI to localize brain activity for Neurosurgical planning. This project is designed to improve fMRI methodology and to perform a thorough comparison between fMRI language mapping and the current gold standard cortical stimulation in patients. This study will determine the ability of fMRI to predict surgical outcome. The patients will have language areas mapped using cortical stimulation and fMRI, and they will undergo behavioral studies pre- and post- surgery in order to measure any deficits that may arise post-surgery. The methodology development will specifically focus on novel techniques we have designed to reduce image distortion in echo planar fMRI, while increasing spatial resolution, and while producing highly robust activation maps even in the presence of field inhomogeneities. Our approach includes modifications to image acquisition strategies in conjunction with new post-processing algorithms. This innovative program will allow for highly robust localization of functional brain regions needed for surgical planning. While the emphasis is on the development and validation of fMRI methodology for Neurosurgical planning in epilepsy, the technical developments will be general and can be applied to any functional MR imaging study. Successful completion of this project may allow fMRI to be used as the primary source of functional localization in the brain for Neurosurgical planning reducing the need for invasive mapping techniques.